This invention relates generally to a photographic camera with improved automatic shutter latch and, more particularly, to a photographic camera having an improved automatic shutter latch with stabilizing means for prohibiting the accidental release of the shutter blades through sudden shock or otherwise together with means for inhibiting the operative influence of the stabilizing means on the blade mechanism during ordinary blade movement.
Electrically driven exposure control systems are advantageous in that they minimize operator requirements of shutter recocking, etc. and are particularly suited for electronic control. For conversation of power, such systems require provision of a stable deenergized shutter condition when the camera is not undergoing exposure operations. An exemplary system of this type is described in U.S. Pat. No. 3820,128 issued to J. T. Burgarella, et al on June 25, 1974 wherein a compact, automated single lens reflex camera is described, and which includes a shutter diaphragm system having shutter blades mechanically biased to an open (viewing) position and electrically biased to a closed position. Advantageously, the exposure system of the above-noted patent is electrically sequenced to provide a precise control over the exposure operation. That is, both the initiation and termination of the exposure interval are electrically, rather than mechanically, determined and, accordingly, may be precisely controlled. However, while the system is particularly adapted for through the lens viewing and provides a normally open shutter, it can be understood that it would also be desirable to provide a normally closed arrangement without compromising the system advantages.
Toward this end, there is described in a copending application for U.S. Patent Serial No. 554,777 entitled "Photographic Apparatus With Sequencing System," by B. Johnson and G. Whiteside, filed March 3, 1975, a latching mechanism provided in order to maintain the shutter blade mechanism in its light blocking position without having to maintain a solenoid in its energy consuming energized state. The means described in the aforementioned patent application for latching and unlatching the shutter blade mechanism comprises a forwardly extending finger arranged for reciprocal movement in correspondence with a film advancing mechanism. The finger is adapted to extend into the locus of movement of the blade mechanism when the film advance mechanism is in its forwardmost position. The shutter blade elements are of the so-called "scanning type" embodying a pivotal walking beam whereby the forward end of the finger provides a rearwardly movable stop, in the path of travel, against which the lower end of the walking beam abuts to prevent clockwise rotation of the walking beam under the influence of a biasing spring. The shutter blade mechanism is unlatched in response to the predetermined rotation of the sequencing gear which causes the film advance mechanism and its associated finger latch to move rearwardly under the influence of another biasing spring. This rearward movement retracts the finger from the path of travel of the walking beam thereby permitting rotation of the beam about its pivot towards the shutter open position. During the course of the cycle of camera operation, the film advance mechanism again moves forwardly to cause the finger to extend through the locus of rotation of the walking beam to relatch the shutter thereby allowing the solenoid to be deenergized.
Another exposure control system utilizing electrically controlled shutter blade elements employing a latch for holding the blades in a light blocking position is more fully described in a copending application for U.S. Patent Serial No. 608,663, entitled "Electro-Mechanical Shutter System Having Mechanical Latch," by L. Douglas, filed Aug. 8, 1975. In accordance with the general concept of the aforementioned invention, the exposure control system includes a reliable shutter latching arrangement which requires shutter actuation for release. Thus, the exposure control system includes a shutter latch released in response to combined electrical and mechanical actuation of the exposure control system. A mechanical shutter latch arrangement is unlocked just before or simultaneously with energization of the exposure control system and then subsequently released in response to initial shutter blade movement resulting from energization of the electrical drive element.
Still another exposure control system having an automatic shutter latch mechanism which may be released in response to initial shutter blade movement resulting from energization of the shutter drive means and which may thereafter be moved into position to accommodate relatching of the shutter blades in response to film advancement is disclosed in a copending application for U.S. Patent Ser. No. 648,225 by Bruce K. Johnson and George D. Whiteside filed Jan. 13, 1976 in common assignement. The shutter latch mechanism of the aforementioned patent application includes a shock stabilizing arrangement to inhibit the accidental unlatching of the shutter blade mechanism resulting from shutter blade movement occasioned through extraneous vibration, sudden shock or otherwise, and not through actuation of the shutter drive means. The stabilizing arrangement, however, may interfere with normal operations of the shutter blade mechanism.
Therefore it is a primary object of this invention to provide an automatic shutter latch mechanism stabilized against accidental release through sudden shock by means not interfering with ordinary operation of the shutter blades during an exposure interval.
It is also an object of this invention to provide an automatic shutter latch mechanism having stabilizer means associated therewith for inhibiting the accidental release of the shutter blade mechanisms through sudden shock or otherwise, together with means for inhibiting the operative influence of the stabilizer means during ordinary operation of the shutter blade elements in the course of a photographic exposure interval.
Other objects of the invention will in part be obvious and will in part appear hereinafter.